1. Field of the Invention
This invention relates to systems for endoscopic treatment of select tissue in living beings (humans or animals) using real-time computer control to visualize, to position and (if desired) to operate drug dispensing, sampling (biopsy); imaging, testing and/or treatment devices within the body of the patient. The invention employs a computerized imaging system (such as CAT scan, MRI imaging, ultrasound imaging, infrared, X-ray, UV/visible light fluorescence, Raman spectroscopy or microwave imaging) to sense the position of an endoscopic treatment system within the body; and, in a preferred embodiment, provides real-time computer control to maintain and adjust the position of the treatment system and/or the position of the patient relative to the treatment system; and also providing (if desired) real-time computer control of the operation of the treatment system itself. Types of treatment systems suitable for use in the invention include surgical tools and tissue manipulators, devices for in vivo delivery of drugs in solid or liquid form; angioplasty devices; biopsy and sampling devices; devices for delivery of RF, thermal, microwave or laser energy or ionizing radiation; and internal illumination and imaging devices, such as modified catheters, endoscopes, laparoscopes and the like instruments, or a combination thereof.
2. Background of the Invention
A variety of endoscopic treatment devices exist, including those containing viewing or imaging systems; devices for endoscopic surgery (such as laser angiosurgery, as in U.S. Pat. No. 5,496,305 (Kittrell, et al.)); biopsy devices and drug delivery systems such as my U.S. Pat. No. 4,900,303 and U.S. Pat. No. 4,578,061. Typically, however, such systems are designed to be manually deployed and positioned by a surgeon and assistants. Surgical personnel must not only treat the patient (i.e., perform the surgical procedure; interpret the images or diagnostic data or obtain the biopsy sample) but also simultaneously maintain the endoscopic device such as a catheter in position (sometimes with great precision) and operate any mechanisms in the device as well, all manually working through a catheter support tube assembly which, desirably, should be as small in diameter as possible to minimize trauma during insertion and operation.
In many diagnosis and treatment situations, precise, real-time positioning of the distal (working) end of the catheter is the key to success with delivering microdoses of drugs that may have high toxicity (e.g. chemotherapeutic agents) as well as directing ionizing radiation or microwaves precisely at the tissue to be altered or destroyed, while minimizing trauma to surrounding, healthy tissue. Precise control of position is also useful in sampling (biopsy) situations to allow samples to be taken from the correct locations within the body.
Nevertheless, internal steering mechanisms for catheters (not to mention real-time control of their position within the body, which is effectively unknown) have been comparatively crude. Catheters, endoscopes, etc. have to be very long and thin, and usually are rather stiff (at least over part of their lengths) to enable them to be advanced through body ducts or directly into tissue without buckling. (Sometimes a removable "split sheath" introducer is used during implantation, and is then split and pulled away from around the catheter, leaving a very pliable catheter in place but incapable of further forward advancement. But, such pliable catheters typically cannot be steered at all, once in place, except for some limited rotation from the outside of the body).
Steerable or positionable catheters typically are rather stiff (and correspondingly traumatic). They may use one or more off-axis pull wires to deflect the distal tip of the catheter by 20.degree. or 30.degree.. The pull wire or wires are fixed at the distal tip of the catheter and extend back to the proximal end. When pulled, they generate off-axis longitudinal forces that deflect the tip toward the side of the catheter where the wire is being pulled. Sometimes, as in U.S. Pat. No. 5,531,677 (Lundquist), only one off-center pull wire is used, in combination with a stiff backbone 180.degree. away, and ribs that make the torque tube preferentially flexible toward the pull wire. (See FIG. 5 of the '677 patent; the pull wire is at reference numeral 48; the backbone is at 32 and the slots 30 between the ribs produce preferential flexibility, creating the arc shown when the wire is pulled. Return forces may be provided by an internal coil spring).
Another system is shown in U.S. Pat. No. 5,531,687 (Snoke, et al.). In that reference, two diametrically opposed pull wires 201 and 202 are wrapped around a central drum or wheel in the handle; rotation of the wheel produces deflection at the tip towards whichever wire is pulled. This permits some limited tip movement in either of two opposite directions (though not in any intermediate directions).
U.S. Pat. No. 4,983,165 (Loiterman) uses an internal guide wire (for stiffness and to prevent buckling) in combination with a plurality of externally-inflatable pouches to force the distal end of a catheter towards (or away from) one wall of a body duct. See FIGS. 4-6 of the Loiterman '165 patent. This arrangement allows the user of a catheter which is passing through a body duct to select one branch of the duct. Such an arrangement would not be usable, however, for a catheter advancing through soft tissue.
U.S. Pat. No. 5,545,200 (West) shows another pull-wire arrangement, in which the pull wire 58 is opposed by a longitudinally-advancable "stiffener member 68" (see FIGS. 3A and 3B). By longitudinally advancing or retracting the stiffener member, the point where curvature begins can be adjusted.
Another approach to adjusting the point of curvature is shown in U.S. Pat. No. 5,533,967 (Imran). The Imran patent shows a central shape-memory element 57 which is made of a shape-memory material, such as Nitinol, which straightens out when heated (as by direct electrical resistance heating) and which is more flexible when not heated. Imran discloses moving an annular "selective conductive bypass means 66" longitudinally along the shape-memory element. Where the bypass means covers (and electrically contacts) the shape memory element, current flows through the bypass rather than through the memory element. In that region, therefore, there is less or no electrical heating and that part of the shape memory element is very flexible. Thus, when one or more pull wires are actuated, the point of flexure occurs at the place where the bypass means has been positioned. Imran also suggests that a plurality of elongate elements 41-43 "having a negative coefficient of [thermal] expansion" could be used in place of moving pull wires to generate the forces needed to cause tip deflection.
Similarly, catheters that are used for imaging typically also must be introduced and positioned manually. Moreover, they lack facility for independently rotating or positioning the sensing or imaging element independently of the manipulating or treatment device in order to focus on a specific area of tissue being treated by drugs, mechanical manipulation or other means. U.S. Pat. No. 5,435,805 (Edwards, et al.), for example, discloses various embodiments of a probing head and, in one embodiment, dual optical lenses (see FIG. 8). Embodiments in FIGS. 15-20 show a needle-like element that is termed a "stylet" or "stylus" for penetrating tissue, such as a prostate, to apply microwave or RF treatment. At column 6, lines 56-60, it is stated that the device can be used in a variety of ways including to deliver liquid (i.e., drug). Positioning of the overall catheter is manual, by means of a torque tube assembly.
U.S. Pat. No. 4,967,745 (Hayes, et al.) discloses a polished end fiber optic cable bundle that forms a lens. A computer control system is adapted to locate healthy or diseased tissue using spectral imaging techniques, and to control a laser to fire pulses of laser radiation down one or more optical fibers to destroy arterial plaque while avoiding damage to healthy tissue. Inflatable balloons inside the catheter, or control wires, may be used to deflect the fiber optic bundle within the catheter. The catheter itself, however, is manually introduced and positioned.
Still further techniques for steering a catheter within the body by altering its shape are disclosed in my co-pending application Ser. No. 08/662,345 (filed Jul. 12, 1996), the disclosure of which is incorporated herein by reference. These techniques utilize electrosensitive gels to alter the rigidity or shape of a catheter.
The prior art approaches, however, are deficient in a number of particulars. They require not only manual introduction, but also more or less constant manual adjustment of position and often of operation. Almost everything is done by hand: the surgeon works by feel, with rudimentary or no imaging capability to guide him and no active computer control to take over so he can concentrate on the operation instead of positioning the catheter and keeping it in position. This increases the number of surgical personnel required, and distracts them from the procedure or diagnosis in progress.
Prior art devices typically also reflect the premise that forces used to alter the shape of the catheter have to be generated and exerted from within the lumen or lumens of the catheter itself (such as by pull wires). Since catheters, endoscopes and other devices, for use inside the body are usually long and thin. This automatically creates problems in obtaining a favorable mechanical advantage for forces that one wants to exert normal to the axis. (In other words, it is necessary to pull the wire(s) very hard in order to generate only a moderate amount of sideways force, since the fulcrum point typically is far back from the area where a bend is desired).